allqueryports is package{
  import volallquery;
  import ports;
  
  RR is p0rt{
    var Folder := relation{
      ("alpha",true);
      ("beta",false);
      ("gamma",true);
    };
    
    DELETE(K) where (K,_) in Folder is valof{
      delete ((Kk,_) where K=Kk) in Folder;
      valis true;
    };
    DELETE(K) default is false;
    
    report() do logMsg(info,"Folder is $Folder");
  };
  
  PP is connectPort_0(RR);
  
  main() do {
    A1 is query PP's Folder with relation of {all X where (X,true) in Folder};
    
    logMsg(info,"$A1");
    assert A1=relation of {"gamma";"alpha"};
  }
}